Brown Adipose Tissues (BAT) are tissues that when activated become metabolically active and take calories from normal white fat and burn them. Safe methods for creating and activating (BAT) would therefore be of great value in fighting obesity, a leading preventable cause of death with increasing prevalence in adults and children and one of the most serious public health problems of the 21st century. Current efforts to develop BAT stimulation paradigms are hindered by the inability to continuously monitor the activity of BAT with available medical scans. Positron Emission Tomography (PET) scans and other similar types of scanners that can detect activated BAT use large, expensive equipment and are only useful for providing single snapshots in time of the existence of activated BAT. The proposed Phase I SBIR program is for the development of monitors that can safely, noninvasively, and continuously record the activity of BAT of an individual over a period of at least 24 hours and that can be worn by the individuals while carrying out their normal activities. The wearable BAT monitors will be miniaturized and improved versions of the large instruments that were successfully used (P<0.01) to detect activated BAT by measuring the microwave thermal noise emitted by activated BAT in a recently completed joint Johns Hopkins University/MMTC R21 program funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) entitled Non-Invasive Measurements of Brown Adipose Tissues, and will include miniaturized devices for storing the measured activity of BAT for periods of at least 24 hours. The availability of wearable continuous BAT activation monitors would be of great value not only in the development of drugs that can activate BAT without causing unacceptable side effects, the first obesity drugs that would affect energy expenditure rather than appetite, but also in answering the following types of important questions: How long do activations and degree of activations of BAT due to exposure to cold last as functions of durations of exposures and temperatures? How long and how deep do deactivations of BAT due to adrenergic beta-blockers last as functions of dosages and are there other widely used drugs that deactivate BAT? To what extend do exercise, diet, smoking, consumption of alcohol, caffeine, type of clothing in cold weather, etc., affect the activity of BAT? For any safe drugs tht can enhance the metabolic activity of BAT, how long does this activation last, how much of such drugs does a particular individual have to take to get a significant increase in the metabolic activity of BAT?